Field of the Invention
The present invention relates to a process for producing of polycrystalline silicon.
Description of the Related Art
Polycrystalline silicon is a material forming a substrate of a semiconductor and a solar cell such as a wafer. This polycrystalline silicon is typically produced by a Siemens method, and this method uses a principle of heating a filament rod mainly made of silicon by applying a current thereto in a bell-type chemical vapor deposition (CVD) reactor, and introducing a raw material gas including a silicon-containing component and hydrogen to deposit silicon on the filament rod.
The silicon-containing component of the raw material used herein is generally halosilane of SiHnX4-n (n=0, 1, 2, 3; X═Cl, Br, I). Chlorosilane or a chlorosilane mixture is preferred, and unreacted trichlorosilane and hydrogen among the components included in an off-gas emitted from the CVD reactor are capable of being used as a raw material in a polycrystalline silicon preparation process, and collecting and recycling these has an advantage of reducing polycrystalline silicon preparation costs.